A combined cycle plant includes a gas turbine that is driven by combustion gas, an exhaust heat recovery boiler that generates steam using heat of the combustion gas discharged from the gas turbine, and a steam turbine that is driven by steam.
Patent Literature 1 discloses a starting method of a combined cycle plant. In this starting method, in order to acquire a main steam temperature which is determined on the basis of a temperature of the steam turbine at the time of start, a temperature of exhaust gas of the gas turbine is controlled such that the temperature of the exhaust gas is equal to or lower than a predetermined upper limit. In the starting method, the upper limit is determined depending on a temperature of a steam contact portion in the steam turbine at the time of start. In the starting method, in order to control the temperature of the exhaust gas, a degree of opening of an inlet guide vane which is disposed in a compressor of the gas turbine is adjusted such that the actual temperature of the exhaust gas is equal to or less than the upper limit.